In faculties for treatments requiring oxygen, such as treatment facilities for animal waste, sludge and sewage, and purification facilities for pond water and boggy water, a diffuser tube-type aeration apparatus is used for jetting air from an air jet hole to perform aeration, wherein the aeration apparatus is operable, under a condition that it is installed in a bottom position of a treatment tank, to jet air from a diffusion tube of an air diffuser to generate air bubbles so as to supply oxygen to a target substance (substance to be treated), such as sewage, to aeration the target substance.
As one example of the diffuser tube-type aeration apparatus, the following Patent Document 1 discloses an aeration apparatus designed to intermittently aerate sewage in an aeration tank while continuously stirring the sewage, to alternately perform an aerobic treatment and an anaerobic treatment, wherein the aeration apparatus is operable, in the aerobic treatment, to jet air from a diffuser tube of an air diffuser to perform aeration, and, when an aerobic period has passed, to stop the aeration to shift to an anaerobic treatment in a next stage.
In regard to an air diffuser for use in an aeration apparatus, for example, a diffuser tube provided with an air jet nozzle is employed (see the following Patent Document 1 to 5).    [Patent Document 1] JP 2006-247586A    [Patent Document 2] JP 2006-198478A    [Patent Document 3] JP 2003-220396A    [Patent Document 4] JP 2001-269692A    [Patent Document 5] JP 9-314169A